| 摘要 |
PURPOSE:To obtain a fire-retardant filter medium having good pleating, flame retarding and dust retaining properties by depositing a flame-retardant chemical on a nonwoven fabric of specified coarse and dense structure. CONSTITUTION:An extrafine fiber with the diameter of the single yarn controlled to <10mum is partially welded by a self-welding fiber, the fiber density is adjusted to 0.07-0.2g/cm<3>, and the fiber density is changed from the upstream side to downstream side of an air current. Namely, the pore size of the coarse part is controlled to >=120mum and that of the dense part to 20-120mum. A fire- retardant chemical is deposited by 40-5wt.% from the surface layer over to the inner layer, and the bending strength of the entire filter medium is controlled to >=200mg. |
